In the practice of dentistry, it is important for the dental professional to have all of the necessary instruments in a convenient and accessible position. To facilitate access to the instruments, it is desirable that they be mounted directly on the dental chair. However, most chairs have electrical elevation systems and back rests designed to tilt upward or downward. It is therefore difficult to mount the instruments to chairs having these features.
Various systems have been designed to hold dental trays on a chair back in a desired position when the back is tilted. U.S. Pat. No. 3,813,147 to Rick and U.S. Pat. No. 4,630,862 to Watanabe disclose systems having this capability. The Rick patent involves an instrument tray in which the tray is attached to the back rest of the chair so that the tray moves upward when the back rest is lowered. The tray includes a support unit having a parallelogram linkage mechanism which maintains the tray horizontally oriented as the back rest is moved between an upright and reclining position. U.S. Pat. No. 4,630,862 to Watanabe discloses a dental chair which also includes an implement table maintained in a level position as the back rest is tilted. A complex system of linkage arms is used, which enables the elevation of the tray to be controlled.
To be effective, a dental instrument delivery system attached to the tiltable back rest of a chair must be capable of maintaining the instruments in a desired position while avoiding the use of complicated linkage systems. Since the chair in a dental office is the most frequently used piece of equipment, reliability is an important consideration.
Furthermore, it is important that the system be designed so that engagement of the system with a stationary object during adjustment of the chair will not result in damage to the instruments it carries. This problem is especially common when modern chairs are used which incorporate electrical means to rapidly raise and lower the chair.
The present invention involves an instrument delivery system which accomplishes the above objectives in a simple and reliable manner. Furthermore, it includes a safety release mechanism which prevents damage to the delivery system and instruments when such items accidentally engage a stationary object during raising and lowering of the chair.